Determining Sex in Chicks

Whether at the feed store choosing day-old chicks or hatching our own, all of us would probably enjoy knowing which chicks are cockerels and which are pullets as soon as possible. Over the past 100 years there have been many methods used to determine the sex of day-old chicks; some methods proved haphazard, some have proven quite effective.

Before we take a look at the methods, it is important to remember the role chance can play in our success. Under normal conditions, a group of chicks generally hatch with 50-55% males and 50-45% females. So that means any method we use to determine the sex of the chicks has about a 50% chance of success – even if the method is erroneous. So if you pick up a chick and guess “pullet” you would be right half the time. For a method to be reliable then, it must be more than 50% accurate every time it is used.

The Egg

Many people think that egg shape can somehow determine the sex of the chick that will hatch. According to this school of thought, pointed or elongated eggs will hatch cockerels and round eggs pullets. I have experimented with this over the years (and there have been scientific studies as well) and the results reveal this method to be nearly useless. Pullets have been hatched from pointed eggs, males from round. If this method had worked, then the poultry industry would have been using this instead of paying for professionals to vent sex day-old chicks.

So how can some people have positive results? Are they lying? Well, in understanding how this method would have any supporters there is the issue of the hen to consider. You see, each hen tends to lay eggs of one shape fairly consistently. Next we need to understand that in avian species sex is not determined by the male, but by the female. The hen has the chromosome which lacks information and by which presence determines sex. Where male humans are XY and female humans XX, roosters are ZZ and hens Z0 (sometimes written ZW). So the male is needed to fertilize the egg, but it is the hen that determines the sex. Also, some hens tend to produce a larger percentage of offspring of one sex, just as in mammals some males tend to produce either more daughters or more sons. Add this all together and you can see that if you have a hen that tends to produce largely daughters and lays round eggs, or produces largely sons and happens to lay pointed eggs, she will “prove” that egg shape determines sex.

Life would be easy for we poultrymen if we could sex the offspring by egg shape. But we cannot.

In breeds with the wild-type color pattern, such as these Light Brown Leghorn chicks, the females have darker dorsal stripes on their backs and up onto their heads while the males have lighter stripes that do not reach their heads. Photos courtesy of Don Schrider.

Temperature

My neighbor is a veteran poultryman and full of knowledge on all subjects poultry. One of the things he pointed out is that incubator temperature affects the percentage of male-to-female chicks. This is not to say that what would be a male chick can convert to female, remember, the hen determines the sex. So what seems to be at work here is survival of the embryo—more females at lower temperature; more males at higher temperature. The adjustment is just a half a degree Fahrenheit up or down.

Weather patterns also seem to have an effect on fertility and on male-to-female percentages in poultry and livestock. This phenomenon has been observed by farmers for centuries. In mammals, it seems to have something to do with conditions favorable to male producing vs. female producing sperm cells. In avians, the effects are likely influencing body temperature of the hen, possibly affecting which sex she produces, but certainly impacting her ability to maintain the semen in a viable state until fertilization.

Temperature is worth further investigation, but do not expect landslide results.

Vent Sexing

Vent Sexing was discovered by the Japanese in 1920 as a reliable and novel approach to determining the sex of day-old chickens. In 1933, Professors Masui and Hashimoto published “Sexing Baby Chickens” in English. In 1934 Dr. Kiyoshi Oxawa visited North America and taught the method in Queensland. From 1935 onward, this method was quickly adopted by large-scale poultry companies across North America. It was the first reliable method of determining the sex of chicks and hatcheries use this method even today.

Vent sexing is a procedure of holding the day-old chick in one hand, spreading open the vent, and viewing the copulatory organs to determine sex based on shape. Warning: there are 18 different shapes possible with a two female and two male shapes that will appear as close matches for the opposite sex. Essentially, the view reveals a shape much like a necklace with “beads” of different sizes, largest in the center. The males have a round/globe-like center “bead”; the females have a flat or concave center “bead.” Skilled vent sexers historically have had a 90% success ratio. Modern reports claim 95%. In any case, this method does work very well, but requires skill and training.

In fast feathering breeds, such as Leghorns, the wing pattern is identical in male and female chicks. This chick is a cockerel.

Down Color

There are many instances when a chick’s down color can reveal its sex. For more than 100 years, possibly more like a thousand years, poultrymen raising chickens with the wild-type color pattern (Black-Breasted Red, Light Brown, Silver Duckwing, etc.) have been able to tell the male chicks from the female chicks at hatch by down color. The males have clean heads with only two colors of dorsal stripes, which often end in a dot at the crown; females have three colors of dorsal stripes, a black or dark brown added outside the other two, and the strips typically run to and through the crown.

Some other pure breeds that can often be sexed at hatch include Barred Plymouth Rocks that produce chicks that are black with spots of yellow or white. Old research demonstrates that there are subtle differences in the light colored down around and on their wings—the males having more light color. But the better method is to note that male chicks tend to have yellow spots on their heads. This will prove true in other Barred or Cuckoo patterned chicken breeds. Both New Hampshires and Buff Orpingtons produce buff colored chicks. If one closely observes these chicks it will be noticed that the male chicks will have off-white streaks in the down color at the upper wing joints. Female chicks will often have a brown or black spot on their heads, or even hints of brown lines on their backs. I have found this true for my Buckeye chicks as well, though they are richer in down color.

When crossing varieties or breeds the chicks often can be sexed based upon down color. The classic cross is of color patterns of gold with those of silver. (In color genetics, gold is the gene that produces red color and silver is the gene that produces white color.) Examples include gold males such as Rhode Island Red, Buff Orpington, New Hampshire crossed to silver females such as Rhode Island White, White Plymouth Rock, Delaware, Light Sussex, White Wyandotte. Male chicks from these crosses will have whitish, grey, or pale brown down. Female chicks will have reddish-brown or buff down. The Dutch have been crossing Golden Campine males to Silver Campine females for centuries to produce chicks that can be sexed at day-old based upon down color.

Using a wild-type, or Black Red male, like Brown Leghorn, Dark Cornish, or BBRed Old English Game, with the silver pattern females yields chicks where the males will have a lighter, grayish color, particularly on the dorsal stripes, and females will have brown stripes and markings. When a non-barred male is used, such as any solid black male, or even an Ancona or Rhode Island Red, the chicks will all be black or dark brown with varying degrees of white in their down—but the male chicks will have a white spot on their heads.

In chicks from sexlink crossbreeds we can often tell the boys from the girls. In Black Sexlinks, the female chicks are black and the male chicks have a white spot on their heads. In the Red Sexlinks (think Golden Comets, ISA Browns, Cinnamon Queens, etc.) the male chicks are often white and the females red or buff. In some cases the males may be buff and the females can be recognized by a black dot on their heads and may have some brown or black lines on their backs.

So the simplest rule in sexing chicks by down color is to remember males have lighter heads, sometimes with a white or yellow spot, and females have darker down color often with a black or brown spot or stripes on their heads or with darker stripes on their backs.

Feather Sexing

It has been found that crossing a fast feathering breed rooster to a slow feathering breed hen will result in chicks in which the pullets will have noticeably better developed wing feathers at birth. By day 10, the cockerels will have caught up on feather development, so check early. In some breeds or strains male and female chicks can also be sexed by looking at their wing feathers at day-old: males will have an even role of feathers and females will have some long and some short, alternating. My Buckeyes are fairly slow feathering and my Brown Leghorns are decidedly fast feathering, but I can see no differences between the sexes with either breed. Still, this method has proven to work for some strains, and might work for yours.

Old Methods

Some early methods of sexing a day-old chick include dangling a ring from a string over the chick—if it moves back and forth the chick is male, if it makes a circle the chick is female. I suppose magnetism is supposed to be at work here, but the end result is that this method does not work.

In some old books there are three very interesting methods. One where the chick is hung upside down in your fingers—female chicks flap and try to right themselves, males just hang. The second method I found very intriguing; that of picking the chick up by the scruff of the neck. In this one if the chick lets it legs hang it is a boy, if it draws its legs up to its breast it is female. This is eliciting a sexual response in the chick. When I first saw this method at work it proved 100% on a handful of chicks. Trying it with my own chicks, whose sex I can tell by down color, proved nearly totally inaccurate. The last method is that of placing the chick on its back in your hand; females will stop kicking after a little while, and males will continue to kick. Again, I observed no positive results.

Other Methods

Time is the big equalizer in determining a chick’s sex. When we first start in poultry it is hard for us to see the differences in the boys and the girls. But as our experience grows, we can often see the differences by three or four weeks of age. So what is it that we learn to look for? In heavy breeds, cockerels will tend to feather in a patchy manner while pullets will feather more evenly. Cockerels also will begin to develop combs at an early age—males being distinguishable by three to four weeks in breeds with large single combs; at six weeks for males with a pea comb. In breeds in which the plumage color varies from male to female, males will begin to show their “true colors” at around six weeks of age. By eight weeks of age males of most breeds will begin to produce long, pointed saddle, hackle, and sickle feathers; females of all breeds tend to have broad, round feathers in these same sections. My Leghorn cockerels even begin crowing between four and six weeks of age!

There are differences in behavior we can notice as well. Cockerels tend to be generally bolder than pullets. They are less likely to scatter if you clap suddenly, whistle, or even wave a hat. When startled, cockerels will stand erect and give a warning chirp, while females are more likely to crouch down and remain silent (except in my Leghorns…). Female chicks may have wider pubic bones than male chicks, though this is only accurate depending on bloodline and selection for egg production. Males also tend to have larger feet and thicker legs than females. This is a trait I have noticed in the Buckeyes at hatch and within a few days in my Leghorns. But it is also a trait that becomes more noticeable as the chicks mature.

Conclusion

The most accurate method for sexing chicks of any breed is that of vent sexing. But for those of us without the desire to learn this method, knowing our stock and observing down color, wing feathering, and development of the chicks still will let us know the boys from the girls at an early age as well. Watch your chicks and see if any of the above methods work for you.

Don Schrider is a nationally recognized poultry breeder and expert. He has written for publications including Backyard Poultry, Countryside and Small Stock Journal, Mother Earth News, Poultry Press, and the newsletter and poultry resources of the American Livestock Breeds Conservancy.

Don is writing a book on raising turkeys. He is interested in hearing from people at all levels of involvement with turkeys: from pets to profession. Please email him at brownleghorn [at] gmail.com.